1. Field of the Invention
The present invention relates to an optical semiconductor device which packages or contains an optical semiconductor element therein, and more particularly to an optical semiconductor device which allows an increase in productivity thereof through a possible simplification to assembling processes, and a method of fabricating the same.
All of patents, patent applications, patent publications, scientific articles and the like, which will hereinafter be cited or identified in the present application, will, hereby, be incorporated by references in their entirety in order to describe more fully the state of the art, to which the present invention pertains.
2. Description of the Related Art
One of the typical optical semiconductor devices is a semiconductor laser device, which has such a structure as packaging a laser diode which is supplied with a current through leads for allowing the laser diode to emit a laser beam. FIG. 1 is a schematic perspective view illustrative of a conventional general structure of a semiconductor laser device. The semiconductor laser device includes a stem 201 having an upper surface united with a post 202, and a plurality of lead 204, which penetrate the stem 201 and are separated by insulation materials 203 from the stem 201, as well as a laser diode LD mounted on one side face of the post 202 and a photo-diode PD mounted on a part of the upper surface of the stem 201.
The laser diode LD and the photo-diode PD are mounted thereon by die-bonding processes. The united structure of the stem 201 and the post 202 may be formed by processing a metal material. Each of the plural leads 204 is electrically connected through a metal wiring 205 to either one of the laser diode LD and the photo-diode PD. The laser diode LD is also electrically connected through the metal wiring 205 to the post 202 or indirectly connected to the stem 201. The semiconductor laser device also includes a cap 206 placed on the upper surface of the stem 201 for covering the above elements mounted over the upper surface of the stem 201. The stem 201 has a generally disk-like shape. The cap 206 has a generally cylinder shape. A periphery of the cap 206 is fusion-spliced with the stem 201. The cap 206 also has a circular-shaped opening window. The metal wirings 205 are provided by a wire bonding process.
The united structure of the stem 201 and the post 202 may be formed by a machining or cutting process for a metal material or by welding the post 202 to the stem 201. Since the stem 201 is made of the metal material, it is necessary to provide the insulating material 203 which electrically isolates the each lead 204 from the stem 201, wherein the each lead 204 is supported via the insulating material 203 to the stem 201. There are many fabrication steps for forming the stem assembly. This makes it difficult to realize desired batch-fabrication processes for processing and assembling plural semiconductor laser devices concurrently. This provides bars to realize desired cost reduction and to improve the accuracy in dimension of the device.
It is further necessary to mount the laser diode LD and the photo-diode PD on the stem assembly, for which purposes, the stem assembly is subjected to the die-bonding process, the wire-bonding process and the fusion-splicing process. In each of those process, the stem assembly is loaded into and unloaded from as well as positioned in each of equipments for taking place those processes. Those processes lower the productivity and make it difficult to realize the desired cost reduction. Lowering the accuracy in positioning of the stem assembly in the equipment causes lowering respective accuracy in the die-bonding process and the wire-bonding process, thereby making it difficult to obtain a high quality semiconductor laser device.
FIG. 2 is a schematic perspective view illustrative of another conventional structure of a semiconductor laser device disclosed in Japanese laid-open patent publication 2001-77262. This conventional technique is to simplify the fabrication processes for the stem assembly. The semiconductor laser device includes a stem 301 which further comprises a cylindrically shaped body 302 with a top narrow rim, a flange 303 united with a bottom peripheral edge of the cylindrically shaped body 302, and an extension strip extending from an inside peripheral edge of the top narrow rim of the cylindrically shaped body 302, wherein the extension strip 304 is bent at a right angle, so that a top of the extension strip extends in a vertical direction to form a vertical plate or a vertical wall which serves as a mount 304. This stem 301 may be formed by a press working from a metal sheet or a metal plate. Further, an insulating material 305 such as a resin material is filled into an inner space of the cylindrically shaped body 302. Plural leads 306 penetrate the insulating material 305, so that the plural leads 306 are supported by the insulating material 305 and electrically separated from the stem 301 by the insulating material 305. A submount 307 is attached onto the mount 304. A laser diode LD and a photodiode PD are mounted on the sub-mount 307. The laser diode LD and the photo-diode PD are electrically connected by a wire-bonding process through metal wirings 308 to the leads 306.
This conventional technique shown in FIG. 2 is advantageous as compared to the above-described conventional technique shown in FIG. 1 in view of simplifying the fabrication processes for the stem and improving the dimensional accuracy of the device. Further, a cap is attached to the stem 301 by the fusion-splicing process, even the illustration of the cap is not omitted in FIG. 2.
Accordingly, the conventional technique shown in FIG. 2 still need the die-bonding process, the wire-bonding process and the fusion-splicing process. In each of those process, the stem assembly is loaded into and unloaded from as well as positioned in each of equipments for taking place those processes. Those processes lower the productivity and make it difficult to realize the desired cost reduction. Lowering the accuracy in positioning of the stem assembly in the equipment causes lowering respective accuracy in the die-bonding process and the wire-bonding process, thereby making it difficult to obtain a high quality semiconductor laser device.
FIG. 3 is a schematic perspective view illustrative of still another conventional structure of a semiconductor laser device disclosed in Japanese laid-open patent publication 2001-68778. Plural leads 301 comprising lead frames are encapsulated with a resin package 302 which has a generally thin box-shape. A sub-mount 303 is provided on a part of one of the leads 301. A photo-diode PD and a laser diode LD are mounted on the sub-mount 303. The photo-diode PD and the laser diode LD are further electrically connected to other ones of the leads 301 through flexible wirings 304. Each of the lead frames may be formed by a press working from a metal sheet or a metal plate. This simplifies the fabrication processes and allows arty improvement in the dimensional accuracy of the lead frames. In this case, the package 302 should have a flat-box-shape as shown in FIG. 3. It is, however, difficult to realize this conventional technique by a can-shaped or cylinder-shaped semiconductor laser device as shown in FIGS. 1 and 2. This flat-box-shaped semiconductor laser device as shown in FIG. 3 is inferior in heat radiation capability as compared to the above-described cylinder-shaped semiconductor laser device as shown in FIGS. 1 and 2. This conventional technique is not applicable to any optical devices including the cylinder-shaped semiconductor laser. It is necessary for applying this conventional technique to change in design of the device.
In the above circumstances, the development of a novel optical semiconductor device free from the above problems is desirable.
Accordingly, it is an object of the present invention to provide a novel optical semiconductor device free from the above problems.
It is a further object of the present invention to provide a novel optical semiconductor device which allows for realizing a high productivity thereof.
It is a still further object of the present invention to provide a novel optical semiconductor device which has a high quality and exhibits high performances.
It is yet a further object of the present invention to provide a novel optical semiconductor device which has a package of a canned-shape or cylinder shape.
It is moreover object of the present invention to provide a novel optical semiconductor device which has a high heat radiation capability.
It is moreover object of the present invention to provide a novel optical semiconductor device which allows for positioning the optical semiconductor device at a high accuracy with reference to a light source position of an optical equipment.
It is still more object of the present invention to provide a novel optical semiconductor device which allows batch fabrication processes for a plurality of the optical semiconductor devices.
It is yet more object of the present invention to provide a novel optical semiconductor device which allows an automated assembling processes for a plurality of the optical semiconductor devices concurrently.
It is another object of the present invention to provide a novel method of forming an optical semiconductor device free from the above problems.
It is further another object of the present invention to provide a novel method of forming an optical semiconductor device which allows for realizing a high productivity thereof.
It is still another object of the present invention to provide a novel method of forming an optical semiconductor device which has a high quality and exhibits high performances.
It is yet another object of the present invention to provide a novel method of forming an optical semiconductor device which has a package of a canned-shape or cylinder shape.
It is an additional object of the present invention to provide a novel method of forming an optical semiconductor device which has a high heat radiation capability.
It is a further additional object of the present invention to provide a novel method of forming an optical semiconductor device which allows for positioning the optical semiconductor device at a high accuracy with reference to a light source position of an optical equipment.
It is a still additional object of the present invention to provide a novel method of forming an optical semiconductor device which allows batch fabrication processes for a plurality of the optical semiconductor devices.
It is yet an additional object of the present invention to provide a novel method of forming an optical semiconductor device which allows an automated assembling processes for a plurality of the optical semiconductor devices concurrently.
The present invention provides an optical semiconductor device includes: an insulating base; and a lead structure which further includes: a flange supported on a first surface of the insulating base; at least a first type lead supported by the insulating base; at least an island for mounting at least an optical semiconductor element thereon, which is electrically connected to the at least first type lead; and at least a connection part extending between the at least island and the flange. The flange, the at least connection part, and the at least island comprise a single united part of the lead structure. The flange, the at least connection part, the at least island, and the at least first type lead comprise a same conductive material.
The above and other objects, features and advantages of the resent invention will be apparent from the following descriptions.